Hey, thank you for listening to the Bryant Park Project from NPR News. You can listen to us FM, Sirius Satellite Radio, digital, online at npr.org/bryantpark. My name's Alison Stewart.

RACHEL MARTIN, host:

And my name is Rachel Martin. Coming up, the life of an NPR foreign correspondent. NPR's Ivan Watson came by, visited with us, and told us what's going on in his head when he visits his home country.

STEWART: Yep, he's on his way back to Istanbul today, I do believe. We'll talk to Ivan in a little bit. But first, let's get some news headlines.

BILL WOLFF: This is NPR.

MARTIN: Thanks, Alison. Barack Obama's campaign says he's won the endorsement of Pennsylvania's Democratic Senator Bob Casey. A campaign spokeswoman says the endorsement will come in Pittsburgh today as Obama begins a campaign swing through the Keystone State. Pennsylvania is the next big prize in the tough contest between Obama and Hilary Clinton.

She holds a double-digit lead in recent voter polls from Pennsylvania with the primary now a little over three weeks away. Casey is a first-term senator and a son of a popular former governor. He's scheduled to join Obama in Pittsburgh today and campaign with him in a cross-state bus tour.

Police closed off the Muslim quarter in the Tibetan capital of Lhasa today. Officers blockaded the streets, allowing in only residents and worshippers observing the Muslim day of prayer. It's not clear why the neighborhood was sectioned off, although rioters had targeted businesses belonging to Chinese Muslims during the protests earlier this month. Responding to growing international criticism, China is allowing foreign diplomats to visit the Tibetan capital today and tomorrow.

A small group of foreign journalists was taken to the city earlier this week. The latest round of fighting between the Iraqi army and the country's most powerful Shiite militias could potentially slow down the pace of U.S. troop withdrawals from Iraq. That's according to the country's most top uniformed officer, Admiral Michael Mullen. Here's NPR's Guy Raz.

GUY RAZ: In an interview with NPR, Admiral Mullen, the chairman of the Joint Chiefs of Staff, says the current fighting has the potential to disrupt already scheduled U.S. troop withdrawals.

Admiral MICHAEL MULLEN (Chairman, U.S. Joint Chiefs of Staff): We're keeping a very close eye on it. And we're very serious about conditions on the ground driving the outcomes here in terms of force rotations, force requirements, you know, all those things.

RAZ: The U.S. military is down-sizing in Iraq by about 4,000 troops a month. Those reductions will last through July, when the president is likely to order a temporary halt, a suggestion recommended by General David Petraeus. Admiral Mullen says he supports the decision and is also seeking to shorten army deployments from the current 15 months to 12.

MARTIN: NPR's Guy Raz reporting. California state regulators have rolled back tough mandates for the number of zero-emission cars that must be sold in the state. The move angered environmentalists and health advocates, who urged officials to keep the strict rules that have also been adopted by 12 other states. Here's NPR's Carrie Kahn.

CARRIE KAHN: State Air Board regulators slashed the number of zero-emission cars in California's near future by 70 percent, a staff recommendation that urged an even greater cut to offset the change. Regulators said the six largest car manufacturers must now sell 60,000 plug-in hybrid vehicles in the state by the year 2014. Regulators say that will give the automakers time to develop the technology needed to mass produce the zero-emission vehicles.

Officials insist the move is not a retreat from California's commitment to put more non-polluting cars on the state's highways. But environmentalists decried the vote, and said the state will not be able to meet its long-term goals to reduce greenhouse gas emissions with the weakened rules. And they say automakers won't produce the cleaner cars unless forced to do so.

MARTIN: NPR's Carrie Kahn reporting. And Puerto Rico's governor is denying corruption allegations. He's accused of taking illegal campaign contributions and filing false tax returns to conceal cash payments he received. Governor Anibal Acevedo Vila says U.S. prosecutors are pursuing a politically-motivated indictment. Acevedo served in Washington as the island's non-voting delegate to Congress, and was elected governor in 2004 after campaigning on an anti-corruption platform. That's the news. It's always online at npr.org.

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